In order to understand the origin of leakage current, light emitting devices were grown on two different templates with apparently different dislocation density: one on thin GaN template (∼2 μm) with higher dislocation density (low × 109 cm–2) prepared by metal‐organic vapor‐phase epitaxy (sample A), and the other on thick GaN template (∼20 μm) with comparatively low dislocation density (high × 108 cm–2) by hydride vapor‐phase epitaxy (sample B). Especially, the template B showed very low value of the dislocation density for a screw component, 2.2 × 107 cm–2 evaluated by transmission electron microscope and 2.3 × 107 cm–2 approximated by the Williamson‐Hall plot which was evaluated by high resolution X‐ray diffraction, respectively. On the other hand, sample A showed one order higher, low × 108 cm–2, than that of sample B for a screw component. Sample A showed the larger leakage current (more than two orders of magnitude) than sample B in a forward‐biased region and a reverse‐biased region also. It is expected that the screw dislocation were strongly contributed to the leakage current of forward and reverse I‐V regions in LEDs. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
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Lee et al. (2007) studied this question.